Short-term benefits of regular exercise

How much exercise do you need?

Just how much exercise do you need to see these benefits? You certainly don't have to join a triathlon club – even moderate exercise such as regular walking or climbing the stairs can be protective no matter how late in life you start.

One thing experts agree on is that your exercise, at the very least, has to be moderately intense and has to be regular. The National Physical Activity Guidelines for Australians recommends at a minimum 30 minutes of moderate physical activity – like walking– on most days of the week. How do you know if you're being moderately active? A good test is to see if you can talk easily while you're exercising. If you can, you are exercising at a light to moderate level. Once your breathing makes it too hard to talk, you know you've increased the intensity of your workout! One thing to remember is that the longer and more intensely you exercise, the greater the benefit. Researchers have found a positive correlation between the length and intensity of physical activity and the reduction in risk of coronary events such as heart attack.

But even short periods of light exercise and daily activities are beneficial if you want to prevent obesity and diabetes. New research shows that sitting around for long periods of time can increase your blood glucose levels – even if you fit a 30 minute session of exercise in – so stay active and complement your 30 minutes of exercise with regular light activity. If you haven't exercised for a while or you want to significantly increase your exercise level, it is advisable to speak with a health professional about designing an exercise plan. Many injuries are caused by exercising too much, too quickly, or by overuse.What types of exercise are there?There are three main types of exercise; each one has a different effect on your body:

Aerobic exercise such as swimming or running increases your cardio respiratory fitness and endurance. This is the capacity of your heart and lungs to supply oxygen-rich blood to your muscles so they can produce energy for movement over a sustained period.

Flexibility exercises such as yoga and Pilates improve the full range of motion of your muscles and joints.

Resistance exercise such as weight-lifting increases your muscle strength by requiring your muscles to lift, push or pull against something. This type of exercise can also increase bone density and help prevent osteoporosis, which is important as you get older. There are several different ways you can strengthen your muscles:

o Isotonic strength training – during this type of training your muscles shorten as they contract. For example when you flex your bicep muscle or do a sit up. This is the most common type of muscle contraction.

o Isometric strength training – during this training the muscle contracts, but the muscle length remains the same. This type of muscle contraction is popular with bodybuilders and occurs when you try to move an immovable object, like pressing against a door frame.

o Eccentric this type of training is the opposite of isotonic training. Your muscles lengthen as they contract, for example when you run down hill.

o Isokinetic strength training – this is similar to isotonic training, except that your muscle contracts at an even speed, for example when your arm moves evenly through the water when swimming.

Choosing the best exercise for you

Getting fit There are several parts to your all over fitness: your cardio respiratory endurance, your muscular strength and endurance, and your flexibility. Ideally your exercise regime for getting fit should work on all three types.

You certainly need strength, cardiovascular endurance and suppleness, but the greater emphasis should be on cardiovascular fitness.

CardiovascularIn terms of health, cardiovascular fitness is one of the greatest predictors of mortality, and has the greatest impact on your ability to do day to day activities. It is recommended you do cardiovascular exercise from between three and five times a week, for either 20 minutes at high intensity or 45 minutes at a lower intensity.

You can test your progress by monitoring your heart rate during exercise. If you do the same exercise every week as a test, your heart rate should be progressively lower week to week as your fitness levels increase.

Strength training Strength training should pop up in your schedule around two to three times a week. The length of your session is less important than making sure you address all the major muscle groups, preferably during exercises that use them simultaneously. Strength exercises that use several parts of your body, rather than just isolating one part are better. You're better off mimicking activities that you find in daily living so they help you cope better.

For older people, strength training is particularly important for bone density, maintaining muscle mass and preventing falls. It's also important in adolescence when your bones are developing their peak density because if you fill the tank up then, your bones will take longer to become osteoporotic in older age.

FlexibilityFlexibility is important for muscle balance, good posture and joint movement, and helps prevent orthopaedic issues later in life. If the muscles around your hip are too tight, for example, this can produce problems in the joint, and can cause the cartilage to wear away.The ideal combination A combination of walking or jogging, cycling or swimming to increase your cardiovascular fitness, and strength training with either weights or doing callisthenic exercises at home or in the park. Calisthenics, like push-ups or chin-ups, use your body weight against gravity and don't require equipment so you can do them anywhere. For flexibility, it's important to do stretches that work on the muscle groups that have common problems with flexibility: the shoulder and chest area, the hips and knees, the back, as well as the gluteals, hamstrings and hip flexors.

Losing weightGetting fit and losing weight go hand in hand. But it's important to remember that it's body-fat loss, not muscle loss that's important for your health. If you just diet and don't exercise, a lot of the weight you lose could be muscle tissue and fluid.It's also important to remember that both structured exercise, like going for a jog, and incidental exercise, like walking to the shops to buy dinner, are both important and you shouldn't increase one at the expense of the other. Some people might start driving to the shops because they're tired from exercise, and then find that their general physical activity levels haven't increased. Remember to keep taking the stairs because that kind of exercise is also really important.

So just how much exercise do you need to lose weight?

One important factor in losing weight is how you balance stocking up on energy and burning it off. If you're eating more than you burn off with your current amount of exercise, you're most likely putting on weight. If you do more exercise – so that you're burning more energy than what's in the food that goes in your mouth – eventually you'll burn off body fat.

If you're after a rough guideline, take the minimum daily requirement – 30 minutes of moderate exercise most days of the week – and double or even triple it, depending on how frisky you're feeling. At 30 minutes a day you're protecting yourself against heart disease and other illness and at 60 to 100 minutes you'll be waving goodbye to those wiggly bits.

Fighting depression More than a million of us suffer from some form of mental illness, including depression and anxiety. Encouragingly, both aerobic exercise and strength training has been successfully used in treating clinical anxiety and depression. One controlled trial found exercise training was as effective as antidepressant medication in older adults, albeit with a slower onset of benefits. We're still unsure of how much you need to exercise to feel the benefits or even why this relationship exists, but researchers are looking for answers, so watch this space.

Recovering from injury Pretty much everyone knows someone who's sprained their ankle playing soccer or pulled a muscle running or done their back in gardening.

Whatever your injury, it's important to see a health professional before you continue exercising. Your GP can give you advice or give you a referral to an exercise physiologist, both of which are covered by Medicare.

Even more important than recovering sensibly from an injury is protecting yourself from one in the first place. Most injuries come from overuse or going too hard, too quickly.

To make sure you don't overdo it at the beginning of your fitness program, start off slow and try out some Fartlek training - when you alternate between a work and active rest period, for example walk-run-walk-run. You might start off with five minutes of walking and two minutes of running, and you gradually increase your working period each time you go out. Eventually you'll be mostly working."

For the avid exerciser, a week off from exercising every 12 weeks or so will help prevent overuse injuries. "You allow the soft tissues to recuperate," says Chris.

Does stretching before exercise help? A review of several studies in 2002 revealed that stretching before and after exercise doesn't stop you from getting aching muscles the next day. The review looked at two studies on army recruits in military training, which both found that stretching before you exercise doesn't reduce your risk of injury. But remember stretching is different to warming up and research has shown a good warm-up can reduce chances of injury.